The present invention relates to an armature winding of a split stator for a rotary electric machine adapted to facilitate the connecting and disassembling of the split stator in a circumferential direction of the rotary electric machine.
When an a.c. rotary electric machine having an armature winding on a stator exceeds a transporting limit on large size, the stator is split in a circumferential direction. in order that it may be disassembled for transport even when sufficient space cannot be provided to axially insert or with a rotor, the stator is split for the purpose of installing at a field site, checking and maintaining the rotary electric machine.
The armature winding of a conventional split stator is arranged as shown in a sectional view of the split stator in FIG. 1. In FIG. 1, the armature has a three-phase, two-layer lap winding formed of a hexagonal-shaped coils for a stator core having two slots for each pole and each phase. Numeral 1 designates a stator core, split in a split surface 1a. Characters X--X designate a split line of the stator. Numeral 2 designates an armature coil inserted into each slot of the stator core 1, the upper port coils 2a are designated by thick lines, and the lower port coils 2b are designated by thin lines. Numerals 3a and 3b designate lead wires of the starting end and finishing end of the coil, and the connecting wires are omitted in FIG. 1. Numeral 4 designates connecting wires between the adjacent armature coils 2 of the same phase.
In a factory for fabricating a rotary electric machine, the split stators are coupled to become a circle, the armature coils 2 are inserted into the respective slots of the stator core 1 and are connected. Thus, the rotor is inserted into and associated with the stator sections of the split stator, and the split stator is then tested in. When the test is finished, the stator is disassembled into units at the split lines for transportation. In this case, the armature coils 2 which cross the split line X--X are removed from the slots. In FIG. 1, six such coils in section A are thus removed.
In this manner, when the rotary electric machine in which the stator is split is assembled and associated at a field site, the armature coils 2 of the split stator that were removed when the stator was disassembled should be again inserted into the slots of the stator core 1.
FIG. 2 shows a sectional view of the split stator of another conventional rotary electric machine having a three phase single-layer chain-winding and two slots for each pole and each phase. A stator core 1 is split at the split plane 1a. Numerals 5 to 8 designate armature coils, solid lines designate U-phase, broken lines designate V-phase and chain lines designate W-phase. Numerals 5a, 7a and 6b, 8b respectively designate the starting end and the finishing end of the coils, and the connecting wires are omitted.
In order to disassemble the split units of the stator of the armature winding of these chain winding coils, the armature coils 5, 6 which cross the split line X--X must first be removed from the slots. In installing them at a field site, the armature coils 5, 6 of the split units to be associated again must be inserted into the coupled stator core 1.
As illustrated and described in the examples above, when the split units of the conventional split stator with the armature winding are disassembled, any armature coil which crosses the split lines should be removed. When the split units of the split stator are then recoupled, the armature coils of the split units should be again inserted into the coupled stator core. However, the armature coils in both cases are insulated against a high voltage, and the insulation of the armature coil may be damaged whenever the wedges used to secure coils in the slots of the stator core 1 are removed and then attached. The removal and insertion of the armature coils from and into the slots of the stator core may damage the insulation. Further, a large amount of labor and time are required for every disassembling and assembling of the split stator.
It has been proposed as another conventional means for removing the armature coils of the split units of the split stator to allow the lower port coils of the armature coils crossing the split line to remain inserted and only the upper port coils of the armature coils to be removed. However, even this procedure will cause a certain amount of damage to the insulation of the armature coils and requires a large quantity of labor and time. Further, this procedure for removing the coils cannot be adopted in situations where the rotor cannot be axially inserted and removed.